/*
 * 文件名：PagePlugin.java
 * 版权：Copyright by www.suyinchina.com
 * 描述：
 * 修改人：WS
 * 修改时间：2015年3月25日
 * 跟踪单号：
 * 修改单号：
 * 修改内容：
 */

package com.suyin.ximoon.plugin.page;

import java.lang.reflect.Field;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
import java.util.Properties;

import javax.xml.bind.PropertyException;

import org.apache.ibatis.executor.ErrorContext;
import org.apache.ibatis.executor.ExecutorException;
import org.apache.ibatis.executor.statement.BaseStatementHandler;
import org.apache.ibatis.executor.statement.RoutingStatementHandler;
import org.apache.ibatis.executor.statement.StatementHandler;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.ParameterMapping;
import org.apache.ibatis.mapping.ParameterMode;
import org.apache.ibatis.plugin.Interceptor;
import org.apache.ibatis.plugin.Intercepts;
import org.apache.ibatis.plugin.Invocation;
import org.apache.ibatis.plugin.Plugin;
import org.apache.ibatis.plugin.Signature;
import org.apache.ibatis.reflection.MetaObject;
import org.apache.ibatis.reflection.property.PropertyTokenizer;
import org.apache.ibatis.scripting.xmltags.ForEachSqlNode;
import org.apache.ibatis.session.Configuration;
import org.apache.ibatis.type.TypeHandler;
import org.apache.ibatis.type.TypeHandlerRegistry;

import com.suyin.ximoon.model.bo.Page;
import com.suyin.ximoon.util.Tools;

@Intercepts({@Signature(type = StatementHandler.class, method = "prepare", args = {Connection.class})})
public class PagePlugin implements Interceptor
{

    private static String dialect = ""; //数据库方言

    private static String pageSqlId = ""; //mapper.xml中需要拦截的ID(正则匹配)

    public Object intercept(Invocation ivk)
        throws Throwable
    {
        // TODO Auto-generated method stub
        if (ivk.getTarget() instanceof RoutingStatementHandler)
        {
            RoutingStatementHandler statementHandler = (RoutingStatementHandler)ivk.getTarget();
            BaseStatementHandler delegate = (BaseStatementHandler)ReflectHelper.getValueByFieldName(
                statementHandler, "delegate");
            MappedStatement mappedStatement = (MappedStatement)ReflectHelper.getValueByFieldName(
                delegate, "mappedStatement");

            if (mappedStatement.getId().matches(pageSqlId))
            { //拦截需要分页的SQL
                BoundSql boundSql = delegate.getBoundSql();
                Object parameterObject = boundSql.getParameterObject();//分页SQL<select>中parameterType属性对应的实体参数，即Mapper接口中执行分页方法的参数,该参数不得为空
                if (parameterObject == null)
                {
                    throw new NullPointerException("parameterObject尚未实例化！");
                }
                else
                {
                    Connection connection = (Connection)ivk.getArgs()[0];
                    String sql = boundSql.getSql();
                    String countSql = "select count(0) from (" + sql + ") as tmp_count"; //记录统计
                    PreparedStatement countStmt = connection.prepareStatement(countSql);
                    BoundSql countBS = new BoundSql(mappedStatement.getConfiguration(), countSql,
                        boundSql.getParameterMappings(), parameterObject);
                    setParameters(countStmt, mappedStatement, countBS, parameterObject);
                    ResultSet rs = countStmt.executeQuery();
                    int count = 0;
                    if (rs.next())
                    {
                        count = rs.getInt(1);
                    }
                    rs.close();
                    countStmt.close();
                    //System.out.println(count);
                    Page page = null;
                    if (parameterObject instanceof Page)
                    { //参数就是Page实体
                        page = (Page)parameterObject;
                        page.setEntityOrField(true); //见com.flf.entity.Page.entityOrField 注释
                        page.setTotalResult(count);
                    }
                    else
                    { //参数为某个实体，该实体拥有Page属性
                        Field pageField = ReflectHelper.getFieldByFieldName(parameterObject,
                            "page");
                        if (pageField != null)
                        {
                            page = (Page)ReflectHelper.getValueByFieldName(parameterObject, "page");
                            if (page == null) page = new Page();
                            page.setEntityOrField(false); //见com.flf.entity.Page.entityOrField 注释
                            page.setTotalResult(count);
                            ReflectHelper.setValueByFieldName(parameterObject, "page", page); //通过反射，对实体对象设置分页对象
                        }
                        else
                        {
                            throw new NoSuchFieldException(parameterObject.getClass().getName()
                                                           + "不存在 page 属性！");
                        }
                    }
                    String pageSql = generatePageSql(sql, page);
                    ReflectHelper.setValueByFieldName(boundSql, "sql", pageSql); //将分页sql语句反射回BoundSql.
                }
            }
        }
        return ivk.proceed();
    }

    /**
     * 对SQL参数(?)设值,参考org.apache.ibatis.executor.parameter.DefaultParameterHandler
     * @param ps
     * @param mappedStatement
     * @param boundSql
     * @param parameterObject
     * @throws SQLException
     */
    @SuppressWarnings({ "rawtypes", "unchecked" })
	private void setParameters(PreparedStatement ps, MappedStatement mappedStatement,
                               BoundSql boundSql, Object parameterObject)
        throws SQLException
    {
        ErrorContext.instance().activity("setting parameters").object(
            mappedStatement.getParameterMap().getId());
        List<ParameterMapping> parameterMappings = boundSql.getParameterMappings();
        if (parameterMappings != null)
        {
            Configuration configuration = mappedStatement.getConfiguration();
            TypeHandlerRegistry typeHandlerRegistry = configuration.getTypeHandlerRegistry();
            MetaObject metaObject = parameterObject == null ? null : configuration.newMetaObject(parameterObject);
            for (int i = 0; i < parameterMappings.size(); i++ )
            {
                ParameterMapping parameterMapping = parameterMappings.get(i);
                if (parameterMapping.getMode() != ParameterMode.OUT)
                {
                    Object value;
                    String propertyName = parameterMapping.getProperty();
                    PropertyTokenizer prop = new PropertyTokenizer(propertyName);
                    if (parameterObject == null)
                    {
                        value = null;
                    }
                    else if (typeHandlerRegistry.hasTypeHandler(parameterObject.getClass()))
                    {
                        value = parameterObject;
                    }
                    else if (boundSql.hasAdditionalParameter(propertyName))
                    {
                        value = boundSql.getAdditionalParameter(propertyName);
                    }
                    else if (propertyName.startsWith(ForEachSqlNode.ITEM_PREFIX)
                             && boundSql.hasAdditionalParameter(prop.getName()))
                    {
                        value = boundSql.getAdditionalParameter(prop.getName());
                        if (value != null)
                        {
                            value = configuration.newMetaObject(value).getValue(
                                propertyName.substring(prop.getName().length()));
                        }
                    }
                    else
                    {
                        value = metaObject == null ? null : metaObject.getValue(propertyName);
                    }
                    TypeHandler typeHandler = parameterMapping.getTypeHandler();
                    if (typeHandler == null)
                    {
                        throw new ExecutorException(
                            "There was no TypeHandler found for parameter " + propertyName
                                + " of statement " + mappedStatement.getId());
                    }
                    typeHandler.setParameter(ps, i + 1, value, parameterMapping.getJdbcType());
                }
            }
        }
    }

    /**
     * 根据数据库方言，生成特定的分页sql
     * @param sql
     * @param page
     * @return
     */
    private String generatePageSql(String sql, Page page)
    {
        if (page != null && Tools.notEmpty(dialect))
        {
            StringBuffer pageSql = new StringBuffer();
            if ("mysql".equals(dialect))
            {
                pageSql.append(sql);
                pageSql.append(" limit " + page.getCurrentResult() + "," + page.getShowCount());
            }
            else if ("oracle".equals(dialect))
            {
                pageSql.append("select * from (select tmp_tb.*,ROWNUM row_id from (");
                pageSql.append(sql);
                pageSql.append(") as tmp_tb where ROWNUM<=");
                pageSql.append(page.getCurrentResult() + page.getShowCount());
                pageSql.append(") where row_id>");
                pageSql.append(page.getCurrentResult());
            }
            return pageSql.toString();
        }
        else
        {
            return sql;
        }
    }

    public Object plugin(Object arg0)
    {
        // TODO Auto-generated method stub
        return Plugin.wrap(arg0, this);
    }

    public void setProperties(Properties p)
    {
        dialect = p.getProperty("dialect");
        if (Tools.isEmpty(dialect))
        {
            try
            {
                throw new PropertyException("dialect property is not found!");
            }
            catch (PropertyException e)
            {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        pageSqlId = p.getProperty("pageSqlId");
        if (Tools.isEmpty(pageSqlId))
        {
            try
            {
                throw new PropertyException("pageSqlId property is not found!");
            }
            catch (PropertyException e)
            {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }
}
